A novel circular RNA, circIgfbp2, links neural plasticity and anxiety through targeting mitochondrial dysfunction and oxidative stress-induced synapse dysfunction after traumatic brain injury.

Traumatic brain injury (TBI) can lead to different neurological and psychiatric disorders. Circular RNAs (circRNAs) are highly expressed in the nervous system and enriched in synapses; yet, the underlying role and mechanisms of circRNAs in neurological impairment and dysfunction are still not fully understood. In this study, we investigated the expression of circRNAs and their relation with neurological dysfunction after TBI. RNA-Seq was used to detect differentially expressed circRNAs in injured brain tissue, revealing that circIgfbp2 was significantly increased. Up-regulated hsa_circ_0058195, which was highly homologous to circIgfbp2, was further confirmed in the cerebral cortex specimens and serum samples of patients after TBI. Moreover, correlation analysis showed a positive correlation between hsa_circ_0058195 levels and the Self-Rating Anxiety Scale scores in these subjects. Furthermore, knockdown of circIgfbp2 in mice relieved anxiety-like behaviors and sleep disturbances induced by TBI. Knockdown of circIgfbp2 in H2O2 treated HT22 cells alleviated mitochondrial dysfunction, while its overexpression reversed the process. Mechanistically, we discovered that circIgfbp2 targets miR-370-3p to regulate BACH1, and down-regulating BACH1 alleviated mitochondrial dysfunction and oxidative stress-induced synapse dysfunction. In conclusion, inhibition of circIgfbp2 alleviated mitochondrial dysfunction and oxidative stress-induced synapse dysfunction after TBI through the miR-370-3p/BACH1/HO-1 axis. Thus, circIgfbp2 might be a novel therapeutic target for anxiety and sleep disorders after TBI.

Phosphoproteomics Reveals Novel Targets and Phosphoprotein Networks in Cell Cycle Mediated by Dsk1 Kinase.

As the ortholog of human SR protein kinase 1 in fission yeast Schizosaccharomyces pombe, Dsk1 specifically phosphorylates SR proteins (serine/arginine-rich proteins) and promotes splicing of nonconsensus introns. The SRPK (SR protein-specific kinase) family performs highly conserved functions in eukaryotic cells including cell proliferation, differentiation, development, and apoptosis. Although Dsk1 was originally identified as a mitotic regulator, its specific targets involved in cell cycle have yet been unexplored. In this study, using a phosphoproteomics approach, we examined differential protein phosphorylation between wild-type cells and dsk1-deletion mutants. We found reduced phosphorylation of 149 peptides corresponding to 133 proteins in the dsk1-null cells. These proteins are involved in various cellular processes, including cytoskeleton organization and signal transduction, and specifically enriched in multiple steps of cell cycle control. Further, targeted MS analyses and in vitro biochemical assays established Cdr2 protein kinase and kinesin motor Klp9 as novel substrates of Dsk1, which function in cell size control for mitotic entry and in chromosome segregation for mitotic exit, respectively. The phosphoprotein networks mediated by Dsk1 reveal, for the first time, the molecular links connecting Dsk1 to mitotic phase transition, sister-chromatid segregation, and cytokinesis, providing further evidence of Dsk1's diverse influence on cell cycle progression and regulation.

Patient-derived xenografts of different grade gliomas retain the heterogeneous histological and genetic features of human gliomas.

BACKGROUND: Gliomas account for the major part of primary brain tumors. Based on their histology and molecular alternations, adult gliomas have been classified into four grades, each with distinct biology and outcome. Previous studies have focused on cell-line-based models and patient-derived xenografts (PDXs) from patient-derived glioma cultures for grade IV glioblastoma. However, the PDX of lower grade diffuse gliomas, particularly those harboring the endogenous IDH mutation, are scarce due to the difficulty growing glioma cells in vitro and in vivo. The purpose of this study was to develop a panel of patient-derived subcutaneous xenografts of different grade gliomas that represented the heterogeneous histopathologic and genetic features of human gliomas. METHODS: Tumor pieces from surgical specimens were subcutaneously implanted into flanks of NOD-Prkdcscid ll2rgnull mice. Then, we analyzed the association between the success rate of implantation with clinical parameters using the Chi square test and resemblance to the patient's original tumor using immunohistochemistry, immunofluorescence, short tandem repeat analysis, quantitative real-time polymerase chain reaction, and whole-exome sequencing. RESULTS: A total of 11 subcutaneous xenografts were successfully established from 16 surgical specimens. An increased success rate of implantation in gliomas with wild type isocitrate dehydrogenase (IDH) and high Ki67 expression was observed compared to gliomas with mutant IDH and low Ki67 expression. Recurrent and distant aggressive xenografts were present near the primary implanted tumor fragments from WHO grades II to IV. The xenografts histologically represented the corresponding patient tumor and reconstituted the heterogeneity of different grade gliomas. However, increased Ki67 expression was found in propagated xenografts. Endothelial cells from mice in patient-derived xenografts over several generations replaced the corresponding human tumor blood vessels. Short tandem repeat and whole-exome sequencing analyses indicated that the glioma PDX tumors maintained their genomic features during engraftments over several generations. CONCLUSIONS: The panel of patient-derived glioma xenografts in this study reproduced the diverse heterogeneity of different grade gliomas, thereby allowing the study of the growth characteristics of various glioma types and the identification of tumor-specific molecular markers, which has applications in drug discovery and patient-tailored therapy.

AKT/GSK-3ß/ß-catenin signaling pathway participates in erythropoietin-promoted glioma proliferation.

PURPOSE: Although erythropoietin (EPO) has been proven to significantly promote the proliferation of cancer cells, the mechanism for promoting glioma proliferation is poorly understood. Here, we examined the functional role of the AKT/GSK-3ß/ß-catenin signaling pathway in the EPO-mediated proliferation of glioma. METHODS: The distribution of EPO and Ki-67 among clinical samples with different WHO grades was plotted by Immunological Histological Chemistry analysis. U87 and U251 glioma cell lines were treated with short hairpin RNA targeting (shEPO), recombinant human erythropoietin (rhEPO) and/or AKT-specific inhibitor (MK-2206). The changes in phosphorylated AKT, nuclear ß-catenin, cyclin D1 and p27kip1 expression were detected. Cell cycle distributions and glioma proliferation in vitro and in vivo were analyzed. RESULTS: The expression level of EPO was significantly elevated with the increase of WHO grade and Ki67 in clinical glioma specimens. In vitro, knockdown of endogenous EPO in U87 and U251 cells effectively block the phosphorylation of AKT and GSK-3ß and the expression of nuclear ß-catenin. shEPO treatment also significantly decreased the expression of cyclin D1 and increased the expression of p27kip1. The cell cycle transition then slowed down and the proliferation of glioma cells or mouse xenograft tumors both decreased. Treatment of cells or tumors with extra rhEPO reversed the above biological effects mediated by shEPO. rhEPO-induced activation of the AKT/GSK-3ß/ß-catenin pathway and proliferation were abolished by MK-2206. CONCLUSIONS: Our study identified the AKT/GSK-3ß/ß-catenin axis as a critical mediator of EPO-induced glioma proliferation and further provided a clinically significant dimension to the biology of EPO.

Interacting factors and cellular localization of SR protein-specific kinase Dsk1.

Schizosaccharomyces pombe Dsk1 is an SR protein-specific kinase (SRPK), whose homologs have been identified in every eukaryotic organism examined. Although discovered as a mitotic regulator with protein kinase activity toward SR splicing factors, it remains largely unknown about what and how Dsk1 contributes to cell cycle and pre-mRNA splicing. In this study, we investigated the Dsk1 function by determining interacting factors and cellular localization of the kinase. Consistent with its reported functions, we found that pre-mRNA processing and cell cycle factors are prominent among the proteins co-purified with Dsk1. The identification of these factors led us to find Rsd1 as a novel Dsk1 substrate, as well as the involvement of Dsk1 in cellular distribution of poly(A)(+) RNA. In agreement with its role in nuclear events, we also found that Dsk1 is mainly localized in the nucleus during G(2) phase and at mitosis. Furthermore, we revealed the oscillation of Dsk1 protein in a cell cycle-dependent manner. This paper marks the first comprehensive analysis of in vivo Dsk1-associated proteins in fission yeast. Our results reflect the conserved role of SRPK family in eukaryotic organisms, and provide information about how Dsk1 functions in pre-mRNA processing and cell-division cycle.

LAMMER kinase Kic1 is involved in pre-mRNA processing.

The LAMMER kinases are conserved through evolution. They play vital roles in cell growth/differentiation, development, and metabolism. One of the best known functions of the kinases in animal cells is the regulation of pre-mRNA splicing. Kic1 is the LAMMER kinase in fission yeast Schizosaccharomyces pombe. Despite the reported pleiotropic effects of kic1+ deletion/overexpression on various cellular processes the involvement of Kic1 in splicing remains elusive. In this study, we demonstrate for the first time that Kic1 not only is required for efficient splicing but also affects mRNA export, providing evidence for the conserved roles of LAMMER kinases in the unicellular context of fission yeast. Consistent with the hypothesis of its direct participation in multiple steps of pre-mRNA processing, Kic1 is predominantly present in the nucleus during interphase. In addition, the kinase activity of Kic1 plays a role in modulating its own cellular partitioning. Interestingly, Kic1 expression oscillates in a cell cycle-dependent manner and the peak level coincides with mitosis and cytokinesis, revealing a potential mechanism for controlling the kinase activity during the cell cycle. The novel information about the in vivo functions and regulation of Kic1 offers insights into the conserved biological roles fundamental to LAMMER kinases in eukaryotes.

Tanshinone IIA reduces AQP4 expression and astrocyte swelling after OGD/R by inhibiting the HMGB1/RAGE/NF-κB/IL-6 pro-inflammatory axis.

This study aimed to investigate the role of tanshinone IIA (TSO IIA) in astrocytic swelling caused by ischemia-reperfusion-like injury in an in vitro model and the molecular mechanisms underlying this effect. Primary brain astrocytes were cultured under conditions of glucose and oxygen deprivation and reoxygenation (OGD/R). The study explored the effects of TSO IIA treatment on cell swelling and injury and the protein levels of aquaporin 4 (AQP4) in the plasma membrane. It then examined the involvement of the high-mobility group box protein 1 (HMGB1)/receptors for advanced-glycation end products (RAGE)/nuclear factor-kappa B (NF-κB)/interleukin-6 (IL-6) pro-inflammatory axis in TSO IIA-mediated protection. The treatment with TSO IIA alleviated OGD/R-induced astrocytic swelling and the overclustering of AQP4 protein in the plasma membrane. In addition, TSO IIA significantly reduced the overexpression of HMGB1 and the high levels of the NF-κB protein in the nucleus and of the IL-6 protein in the cytoplasm and extracellular media induced by OGD/R. The combination of TSO IIA and recombinant HMGB1 reversed these effects. The inhibition of the RAGE, the receptor of HMGB1, induced results similar to those of TSO IIA. In addition, exogenous IL-6 reversed TSO IIA-mediated effect on AQP4 overclustering and cell swelling. TSO IIA significantly reduced astrocyte swelling after OGD/R injury in vitro, via blocking the activation of the HMGB1/RAGE/NF-κB/IL-6 pro-inflammatory axis and thereby decreasing the expression of AQP4 in the plasma membrane.

Protective effects and regulatory pathways of melatonin in traumatic brain injury mice model: Transcriptomics and bioinformatics analysis.

Traumatic brain injury (TBI) is the leading cause of disability and mortality globally. Melatonin (Mel) is a neuroendocrine hormone synthesized from the pineal gland that protects against TBI. Yet, the precise mechanism of action is not fully understood. In this study, we examined the protective effect and regulatory pathways of melatonin in the TBI mice model using transcriptomics and bioinformatics analysis. The expression profiles of mRNA, long non-coding RNA (lncRNA), microRNA (miRNA), and circular RNA (circRNA) were constructed using the whole transcriptomes sequencing technique. In total, 93 differentially expressed (DE) mRNAs (DEmRNAs), 48 lncRNAs (DElncRNAs), 59 miRNAs (DEmiRNAs), and 59 circRNAs (DEcircRNAs) were identified by the TBI mice with Mel treatment compared to the group without drug intervention. The randomly selected coding RNAs and non-coding RNAs (ncRNAs) were identified by quantitative real-time polymerase chain reaction (qRT-PCR). To further detect the biological functions and potential pathways of those differentially expressed RNAs, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses were executed. In our research, the regulatory network was constructed to show the relationship of lncRNA-RBPs. The lncRNA-mRNA co-expression network was established based on the Pearson coefficient to indicate the expression correlations. Moreover, the DEcircRNA-DEmiRNA-DEmRNA and DElncRNA-DEmiRNA-DEmRNA regulatory networks were constructed to demonstrate the regulatory relationship between ncRNAs and mRNA. Finally, to further verify our predicted results, cytoHubba was used to find the hub gene in the synaptic vesicle cycle pathway, and the expression level of SNAP-25 and VAMP-2 after melatonin treatment were detected by Western blotting and immunofluorescence. To sum up, these data offer a new insight regarding the molecular effect of melatonin treatment after TBI and suggest that the high-throughput sequencing and analysis of transcriptomes are useful for studying the drug mechanisms in treatment after TBI.

Fission Yeast Schizosaccharomyces pombe: A Unicellular "Micromammal" Model Organism.

The fission yeast Schizosaccharomyces pombe is a rod-shaped unicellular eukaryote, well known for its contributions as a model organism for our understanding of regulation and conservation of the eukaryotic cell cycle. As a yeast divergent from the budding yeast Saccharomyces cerevisiae, S. pombe shares more common features with humans including gene structures, chromatin dynamics, and the prevalence of introns, as well as the control of gene expression through pre-mRNA splicing, epigenetic gene silencing, and RNAi pathways. With the advent of new methodologies for research, S. pombe has become an increasingly used model to investigate various molecular and cellular processes over the last 50 years. Also, S. pombe serves as an excellent system for undergraduate students to obtain hands-on research experience. Versatile experimental approaches are amenable using the fission yeast system due to its relative ease of maintenance, its inherent cellular properties, its power in classic and molecular genetics, and its feasibility in genomics and proteomics analyses. This article provides an overview of S. pombe's rise as a valuable model organism and presents examples to highlight the significance of S. pombe as a unicellular "micromammal" in investigating biological questions. We especially focus on the advantages of and the advancements in using fission yeast for studying biological processes that are characteristic of metazoans to decipher the underlining molecular mechanisms fundamental to all eukaryotes. © 2021 Wiley Periodicals LLC.

Correlation Between SNPs at the 3'UTR of the FGF2 Gene and Their Interaction with Environmental Factors in Han Chinese Diabetic Peripheral Neuropathy Patients.

FGF2 is a neurotrophic factor that can act as a key regulatory molecule of neuroprotection, neurogenesis, and angiogenesis in various injuries. To explore the genetic background of the FGF2 gene on DPN development, this study analyzed the correlation between SNPs in the 3'UTR of the FGF2 gene and their interaction with environmental factors in DPN patients of Han Chinese nationality. Sanger sequencing was used to analyze the FGF2 genotypes at the rs1048201, rs3804158, rs41348645, rs6854081, rs3747676, rs7683093, rs1476215, and rs1476217 loci in 150 DPN patients, 150 NDPN patients, and 150 healthy control patients. Plasma FGF2 levels were measured in all subjects by using ELISAs. Subjects carrying the T allele at the rs1048201 locus in the FGF2 gene had a significantly lower risk of developing DPN compared with subjects carrying the C allele (OR = 0.43, 95% CI = 0.33-0.56, p < 0.01). Subjects with the G genotype at the rs6854081 locus had an exceptionally higher risk of developing DPN than subjects with the T allele (OR = 1.66, 95% CI = 1.39-1.89, p < 0.01). Individuals harboring the G allele at the rs7683093 locus had a markedly higher risk of DPN than patients with the C allele (OR = 1.63, 95% CI = 1.36-1.87, p < 0.01). Finally, individuals having the A genotype at the rs1476215 locus had a significantly higher risk of DPN than individuals carrying the T allele (OR = 1.82, 95% CI = 1.53-2.02, p < 0.01). There was an interaction between age and alcohol consumption and the SNP rs7683093. SNPs at rs1048201, rs6854081, rs7683093, and rs1476215 in the FGF2 3'UTR were strongly associated with plasma levels of FGF2 (p < 0.05). SNPs at the rs1048201, rs6854081, rs7683093, and rs1476215 loci in the FGF2 gene were significantly associated with the risk of DPN. A possible mechanism is that these SNPs affect the expression level of FGF2 by interrupting the binding of microRNAs to target sites in the 3'UTR.

[Blocking ERK signaling pathway lowers MMP-9 expression to alleviate brain edema after traumatic brain injury in rats].

OBJECTIVE: To investigate the effects of blocking the activation of ERK pathway on the expression of matrix metalloproteinase-9 (MMP-9) and the formation of cerebral edema in SD rats after brain injury. METHODS: Ninety SD rats were randomly divided into 3 equal groups, including a sham-operated group, modified Feeney's traumatic brain injury model group, and ERK inhibition group where the ERK inhibitor SCH772984 (500 µg/kg) was injected via the femoral vein 15 min before brain trauma. At 2 h and 2 days after brain trauma, the permeability of blood-brain barrier was assessed by Evans blue method, the water content of the brain tissue was determined, and the phosphorylation level of ERK and the expression level of MMP-9 mRNA and protein were measured by RT-PCR and Western blotting. RESULTS: Compared with the sham-operated group, the rats with brain trauma exhibited significantly increased level of ERK phosphorylation at 2 h and significantly increased expression of MMP-9 mRNA and protein 2 days after the injury (P < 0.01). Treatment with the ERK inhibitor significantly decreased the phosphorylation level of ERK after the injury (P < 0.01), suppressed over-expression of MMP-9 mRNA and protein 2 days after the injury (P < 0.01). The permeability of blood-brain barrier increased significantly 2 h after brain trauma (P < 0.05) and increased further at 2 days (P < 0.01); the water content of the brain did not change significantly at 2 h (P > 0.05) but increased significantly 2 d after the injury (P < 0.01). Treatment with the ERK inhibitor significantly lowered the permeability of blood-brain barrier and brain water content after brain trauma (P < 0.01). CONCLUSIONS: Blocking the activation of ERK pathway significantly reduced the over-expression of MMP-9 and alleviates the damage of blood-brain barrier and traumatic brain edema, suggesting that ERK signaling pathway plays an important role in traumatic brain edema by regulating the expression of MMP-9.

Comparative Genomic Screen in Two Yeasts Reveals Conserved Pathways in the Response Network to Phenol Stress.

Living organisms encounter various perturbations, and response mechanisms to such perturbations are vital for species survival. Defective stress responses are implicated in many human diseases including cancer and neurodegenerative disorders. Phenol derivatives, naturally occurring and synthetic, display beneficial as well as detrimental effects. The phenol derivatives in this study, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and bisphenol A (BPA), are widely used as food preservatives and industrial chemicals. Conflicting results have been reported regarding their biological activity and correlation with disease development; understanding the molecular basis of phenol action is a key step for addressing issues relevant to human health. This work presents the first comparative genomic analysis of the genetic networks for phenol stress response in an evolutionary context of two divergent yeasts, Schizosaccharomyces pombe and Saccharomyces cerevisiae Genomic screening of deletion strain libraries of the two yeasts identified genes required for cellular response to phenol stress, which are enriched in human orthologs. Functional analysis of these genes uncovered the major signaling pathways involved. The results provide a global view of the biological events constituting the defense process, including cell cycle arrest, DNA repair, phenol detoxification by V-ATPases, reactive oxygen species alleviation, and endoplasmic reticulum stress relief through ergosterol and the unfolded protein response, revealing novel roles for these cellular pathways.

Dsk1p kinase phosphorylates SR proteins and regulates their cellular localization in fission yeast.

Evolutionarily conserved SR proteins (serine/arginine-rich proteins) are important factors for alternative splicing and their activity is modulated by SRPKs (SR protein-specific kinases). We previously identified Dsk1p (dis1-suppressing protein kinase) as the orthologue of human SRPK1 in fission yeast. In addition to its similarity of gene structure to higher eukaryotes, fission yeast Schizosaccharomyces pombe is a unicellular eukaryotic organism in which alternative splicing takes place. In the present study, we have revealed for the first time that SR proteins, Srp1p and Srp2p, are the in vivo substrates of Dsk1p in S. pombe. Moreover, the cellular localization of the SR proteins and Prp2p splicing factor is dependent on dsk1(+): Dsk1p is required for the efficient nuclear localization of Srp2p and Prp2p, while it promotes the cytoplasmic distribution of Srp1p, thereby differentially influencing the destinations of these proteins in the cell. The present study offers the first biochemical and genetic evidence for the in vivo targets of the SRPK1 orthologue, Dsk1p, in S. pombe and the significant correlation between Dsk1p-mediated phosphorylation and the cellular localization of the SR proteins, providing information about the physiological functions of Dsk1p. Furthermore, the results demonstrate that the regulatory function of SRPKs in the nuclear targeting of SR proteins is conserved from fission yeast to human, indicating a general mechanism of reversible phosphorylation to control the activities of SR proteins in RNA metabolism through cellular partitioning.

[Erythropoietin accelerates the proliferation of glioma cells via activating Akt pathway].

OBJECTIVE: To determine whether erythropoietin (EPO) promotes rapid proliferation of glioma through Akt pathway. METHODS: We detected the expression of EPO in human glioma tissues using immunohistochemistry. A nude mouse model bearing human glioma U87 cell xenograft was established and given intraperitoneal injection of EPO or saline every other day, and the tumor growth was observed. In the in vitro experiment, U87 cells were treated with PBS (control), EPO, or EPO with Akt inhibitor, and the expression of p-Akt and cyclin D1 was detected using Western blotting; the cell proliferation rate was determined using cell counting kit-8 and clone formation assay, and the cell cycle changes were analyzed with flow cytometry. RESULTS: Compared with low-grade glioma tissues, high-grade glioma tissues exhibited a significantly increased EPO expression (P=0.0002). In the tumor-bearing mice, EPO treatment significantly increased the expression of EPO (P=0.0006) and p-Akt (P=0.0003) in the tumor and obviously increased the tumor volume (P<0.0001) and weight (P=0.0003). In U87 cells cultured in vitro, EPO treatment obviously accelerated the cell proliferation (P=0.020 on day 3 and 0.028 on day 5), promoted clone formation (P=0.0010), and increased proliferation index (P=0.0028); EPO significantly enhanced the protein expression of p-Akt (P=0.0020) and cyclin D1 (P=0.0022). The application of Akt inhibitor significantly suppressed the effect of EPO in enhancing cyclin D1 and p-Akt expression (both P<0.0001) and promoting cell proliferation. CONCLUSION: EPO can significantly accelerate the proliferation of glioma through Akt pathway.

Phosphorylation by SR kinases regulates the binding of PTB-associated splicing factor (PSF) to the pre-mRNA polypyrimidine tract.

PSF (PTB-associated splicing factor) is a multi-functional protein that participates in transcription and RNA processing. While phosphorylation of PSF has been shown to be important for some functions, the sites and the kinases involved are not well understood. Although PSF does not contain a typical RS domain, we report here that PSF is phosphorylated in vivo to generate an epitope(s) that can be recognized by a monoclonal antibody specific for phosphorylated RS motifs within SR proteins. PSF can be phosphorylated by human and yeast SR kinases in vivo and in vitro at an isolated RS motif within its N terminus. A functional consequence of SR phosphorylation of PSF is to inhibit its binding to the 3' polypyrimidine tract of pre-mRNA. These results indicate that PSF is a substrate of SR kinases whose phosphorylation regulates its RNA binding capacity and ultimate biological function.

Upregulation of DACT2 suppresses proliferation and enhances apoptosis of glioma cell via inactivation of YAP signaling pathway.

DACT2, one of the Dact gene family members, was shown to function as a tumor suppressor. However, its function in gliomas remains largely unknown. In this study, we investigated the role of DACT2, underlying molecular mechanisms and its clinical significance in glioma patients. Downexpression of DACT2 in gliomas compared with adjacent normal brain tissues was correlated with glioma grade and poor survival. Cox regression analysis revealed that the DACT2 is an independent prognostic indicator for glioma patients. Overexpression of DACT2 in glioma cells inhibited proliferation, cell cycle and enhanced apoptosis, sensitivity to temozolomide in vitro and suppressed tumor growth in vivo. Whereas knockdown of DACT2 induce opposite reaction. Mechanistically, overexpression of DACT2 resulted in upregulation of important signaling molecules such as p-YAP and p-ß-catenin, and prevent YAP translocating into nucleus and sequestering in the cytoplasm to degrade. The study further proved that DACT2 can suppress YAP through Wnt/ß-catenin signaling pathway. Collectively, these data indicate that DACT2 has a tumor suppressor function via inactivation of YAP pathway, providing a promising target for the treatment of gliomas.

Model Organisms for Studying the Cell Cycle.

Regulation of the cell-division cycle is fundamental for the growth, development, and reproduction of all species of life. In the past several decades, a conserved theme of cell cycle regulation has emerged from research in diverse model organisms. A comparison of distinct features of several diverse model organisms commonly used in cell cycle studies highlights their suitability for various experimental approaches, and recaptures their contributions to our current understanding of the eukaryotic cell cycle. A historic perspective presents a recollection of the breakthrough upon unfolding the universal principles of cell cycle control by scientists working with diverse model organisms, thereby appreciating the discovery pathways in this field. A comprehensive understanding is necessary to address current challenging questions about cell cycle control. Advances in genomics, proteomics, quantitative methodologies, and approaches of systems biology are redefining the traditional concept of what constitutes a model organism and have established a new era for development of novel, and refinement of the established model organisms. Researchers working in the field are no longer separated by their favorite model organisms; they have become more integrated into a larger community for gaining greater insights into how a cell divides and cycles. The new technologies provide a broad evolutionary spectrum of the cell-division cycle and allow informative comparisons among different species at a level that has never been possible, exerting unimaginable impact on our comprehensive understanding of cell cycle regulation.

The Crucial Role of Cyclin-Dependent Kinase-5-Ataxia-Telangiectasia Mutated Axis in ICH-Induced Neuronal Injury of Rat Model.

Cyclin-dependent kinase 5 (CDK5) and ataxia-telangiectasia mutated (ATM) are involved in normal human neurodevelopment and serves as a switch between neuronal survival and death. However, the molecular mechanisms underlying CDK5-ATM-induced neuronal injury caused by intracerebral hemorrhage (ICH) remain unclear. In this work, we used rat ICH models and thrombin-induced cell models to investigate the potential role of CDK5-ATM signals. Our findings revealed that CDK5 protein levels and kinase activities (p-histone H1 expression) were enforced in hematoma-surrounding neuron tissues following ICH. Besides, the expression of p25, p-ATM, and active caspase-3 protein was also upregulated after ICH. According to in vitro assays, the expression of CDK5, p-ATM, and active caspase-3 was all upregulated in cell viability-decreasing ICH cell models. However, blocking of either CDK5 or ATM suppressed the phosphorylation of ATM and the expression of active caspase-3, and attenuated the inhibition of neuronal survival. When p35/p25 was silenced, CDK5-ATM pathway was further inhibited, and cell viability was obviously ameliorated. In conclusion, this work suggested that ATM could be phosphorylated by CDK5 to induce the active caspase-3 and neuronal injury when intracerebral hemorrhage or ischemia occurred. Thus, the CDK5-AMT signal pathway has an important role in ICH process and may be a therapeutic target to prevent brain injury.

Neuroligin-1 Knockdown Suppresses Seizure Activity by Regulating Neuronal Hyperexcitability.

Abnormally synchronized synaptic transmission in the brain leads to epilepsy. Neuroligin-1 (NL1) is a synaptic cell adhesion molecule localized at excitatory synapses. NL1 modulates synaptic transmission and determines the properties of neuronal networks in the mammalian central nervous system. We showed that the expression of NL1 and its binding partner neurexin-1ß was increased in temporal lobe epileptic foci in patients and lithium-pilocarpine-treated epileptic rats. We investigated electrophysiological and behavioral changes in epileptic rats after lentivirally mediated NL1 knockdown in the hippocampus to determine whether NL1 suppression prevented seizures and, if so, to explore the probable underlying mechanisms. Our behavioral studies revealed that NL1 knockdown in epileptic rats reduced seizure severity and increased seizure latency. Whole-cell patch-clamp recordings of CA1 pyramidal neurons in hippocampal slices from NL1 knockdown epileptic rats revealed a decrease in spontaneous action potential frequency and a decrease in miniature excitatory postsynaptic current (mEPSC) frequency but not amplitude. The amplitude of N-methyl-D-aspartate receptor (NMDAR)-dependent EPSCs was also selectively decreased. Notably, NL1 knockdown reduced total NMDAR1 expression and the surface/total ratio in the hippocampus of epileptic rats. Taken together, these data indicate that NL1 knockdown in epileptic rats may reduce the frequency and severity of seizures and suppress neuronal hyperexcitability via changes in postsynaptic NMDARs.